During hay production, timing and storage have the most significant impact on hay’s overall quality. In order to prevent losses, farmers need to understand how these factors impact hay quality in order to mitigate losses. Today, storage losses of uncovered hay can reach upwards of 30%. These losses, including respiration and weather, have resulted in one of the largest outlets for lost dollars in livestock operations. Below are some of the most common types of hay losses and what factors influence them.
Dry Matter Losses
After harvest, dry matter loss can occur due to plant respiration, even with hay that has less than 20% dry matter. During times when harvest moisture levels reach more than 20%, mild is far more likely to spread, causing a greater degree of dry matter loss due to microbial activity. According to one study performed by the University of Tennessee, bales that have been placed under a hay barn show a 5% loss while stacked or tarped hay bales show a 14%. Round bales were reported as having a 23%, while uncovered hay bales showed a total loss of 30%. In order to reduce storage losses, hay harvesters must limit moisture reaching their hay by using plastic tarps, net wraps, or a hay barn. Allhay.com recommends using pallets or gravel lots to prevent bales from remaining on the ground and near moisture for those who do not have access to these resources.
Forage Quality Losses
A variety of studies have found that storage conditions of hay can also have a severe impact on hay’s chemical composition and thus its overall feeding value. Typically, storage conditions on unweathered and weathered hay barrels will mostly impact crude proteins, acid detergent fibers, and in vitro digestible dry matter. Scientists have found that even when there are little to no dry matter losses or additional feeding losses with weathered hay, forage quality remains a major concern. This is because crude protein declines with weathering, but the percentage of crude protein often increases due to dry matter loss.
Some of the factors that often affect the amount of total forage loss due to weather include weather and climate condition during storage, bale density, and hay species (timothy hay, grass hay, etc). Oftentimes, uncovered hay loses quality thanks to rain moving through the bale and removing water-soluble carbohydrates of the plant cell, causing a loss in the hay’s total digestible nutrients.